arm64: save and restore cntfrq for secondary cpus

CNTFRQ_EL0 can only be set in highest implemented exception level.
Save and restore CNTFRQ_EL0 for secondary cpus in coreboot.

This patch fix the error below:

SANITY CHECK: Unexpected variation in cntfrq. Boot CPU:
0x00000000c65d40, CPU1: 0x00000000000000

BRANCH=none
BUG=none
TEST=boot to kernel on oak board and check secondary cpu's cntfrq.
     confirmed cpu1's cntfrq is same as boot cpu's.

Change-Id: I9fbc3c82c2544f0b59ec34b1d631dadf4b9d40eb
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: b47e4e649efc7f79f016522c7d8a240f98225598
Original-Signed-off-by: Jimmy Huang <jimmy.huang@mediatek.com>
Original-Change-Id: I2d71b0ccfe42e8a30cd1367d10b0f8993431ef8c
Original-Reviewed-on: https://chromium-review.googlesource.com/264914
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9921
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/arch/arm64/armv8/lib/sysctrl.c

@@ -1051,3 +1051,18 @@ void raw_write_vbar(uint64_t vbar, uint32_t el)
 {
 	SWITCH_CASE_WRITE(raw_write_vbar, vbar, el);
 }
+
+uint32_t raw_read_cntfrq_el0(void)
+{
+	uint32_t cntfrq_el0;
+
+	__asm__ __volatile__("mrs %0, CNTFRQ_EL0\n\t" : "=r" (cntfrq_el0) : :
+			     "memory");
+	return cntfrq_el0;
+}
+
+void raw_write_cntfrq_el0(uint32_t cntfrq_el0)
+{
+	__asm__ __volatile__("msr CNTFRQ_EL0, %0\n\t" : : "r" (cntfrq_el0) :
+			     "memory");
+}

src/arch/arm64/include/arch/startup.h

@@ -29,8 +29,9 @@
 #define TTBR0_INDEX			2
 #define SCR_INDEX			3
 #define VBAR_INDEX			4
+#define CNTFRQ_INDEX			5
 /* IMPORTANT!!! If any new element is added please update NUM_ELEMENTS */
-#define NUM_ELEMENTS			5
+#define NUM_ELEMENTS			6
 
 #ifndef __ASSEMBLY__
 

src/arch/arm64/include/armv8/arch/lib_helpers.h

@@ -261,6 +261,16 @@
 402:
 .endm
 
+/* Macro to read from an el0 register */
+.macro read_el0 xreg sysreg
+	mrs	\xreg, \sysreg\()_el0
+.endm
+
+/* Macro to write to an el0 register */
+.macro write_el0 sysreg xreg temp
+	msr	\sysreg\()_el0, \xreg
+.endm
+
 /* Macro to invalidate all stage 1 TLB entries for current EL */
 .macro tlbiall_current temp
 	switch_el \temp, 401f, 402f, 403f
@@ -547,6 +557,8 @@ uint64_t raw_read_vbar_current(void);
 void raw_write_vbar_current(uint64_t vbar);
 uint64_t raw_read_vbar(uint32_t el);
 void raw_write_vbar(uint64_t vbar, uint32_t el);
+uint32_t raw_read_cntfrq_el0(void);
+void raw_write_cntfrq_el0(uint32_t cntfrq_el0);
 
 /* Cache maintenance system instructions */
 void dccisw(uint64_t cisw);

src/arch/arm64/stage_entry.S

@@ -190,6 +190,9 @@ ENDPROC(__rmodule_entry)
 	get_element_addr VBAR_INDEX
 	write_current vbar, x0, x1
 
+	get_element_addr CNTFRQ_INDEX
+	write_el0 cntfrq, x0, x1
+
 	dsb sy
 	isb
 

src/arch/arm64/startup.c

@@ -45,6 +45,7 @@ void startup_save_cpu_data(void)
 	save_element(TCR_INDEX, raw_read_tcr_current());
 	save_element(TTBR0_INDEX, raw_read_ttbr0_current());
 	save_element(VBAR_INDEX, raw_read_vbar_current());
+	save_element(CNTFRQ_INDEX, raw_read_cntfrq_el0());
 
 	if (get_current_el() == EL3)
 		save_element(SCR_INDEX, raw_read_scr_el3());